In the field of wireless cellular communication recent developments of wireless cellular standards, in particular LTE-Cat1, are mainly designed for low-cost (LC) devices, in particular in the field of machine type communication (MTC). Those devices are often situated in areas with bad reception conditions, e.g. metering devices in cellars.
As part of the 3GPP Release 13 definition for such LC devices it was suggested the so-called enhanced coverage (EC) mode. This solves said reception issues by allowing communication that way that by many repetitive receptions of the same data packets the receiver aggregates sufficient power gain until the data packets can be reliably read from the receiver. As a precondition the wireless device and the serving base node need to agree upon registration of the wireless device at the base node that on both sides of the air interface the enhanced coverage mode is activated. A precondition for that is that the base node supports EC devices, otherwise they were barred on that base node. The enhanced coverage support is performed up to a certain coverage enhancement limit which is also indicated by the base node, i.e. corresponding to the maximum of repetitions and resources a base node would spend for a user to achieve a certain coverage enhancement depth.
As many of such low-cost devices nowadays are operating in older wireless technology standards, in particular 2G, which encompasses the standards GSM, GPRS or EDGE, it is also discussed the option of introducing such enhanced coverage methods also in 2G. As the hardware requirements are low, it is likely that both wireless devices and the respective base nodes need only updates of the firmware for supporting enhanced coverage.
In the following enhanced coverage support which is related to a wireless technology standard other than LTE is called extended coverage mode. Main difference is here that for GSM extended coverage may to some extend be realized on existing hardware, i.e. just via a software update.
The concept of extended coverage for GSM is in particular defined in 3GPP TSG GERAN for GSM as Extended Coverage GSM (EC-GSM) as described for example in TD GPE150064 “CR 43.064-0090 Introduction of EC-EGPRS, Definitions and general feature description (Rel-13)” (Ericsson), which is incorporated herein by reference.
It is however a problem that depending on the capabilities of the wireless device, in particular its hardware equipment, not all wireless devices are capable to fully support extended coverage mode. The obvious solution only to allow extended coverage mode for those wireless devices which are fully capable of supporting this mode would leave out too much devices, in particular those who are capable to a certain extent of supporting extended coverage.
This applies in particular to those devices which are capable of supporting a certain amount of repetitions. This is in particular limited due to memory restrictions for averaging received signals and the phase stability of the used amplifiers depending on phase shifts in the uplink.
Here is where the invention is coming in, which allows also to support extended coverage mode for those devices, which are not capable of fully supporting the extended coverage mode, and hence to spread out this mode in particular to devices with cheaper hardware fitments.
It is therefore the goal of present invention to propose an improved solution for an operation of wireless devices in extended coverage mode.
Further alternative and advantageous solutions would, accordingly, be desirable in the art.